A brushless permanent magnet motor usually comprises a permanent magnet rotor and a stator with stator windings. The stator windings, when electrified, generate a rotating magnetic field to rotate the rotor. Rare earth magnets with high magnetic strength are commonly used for rotor magnets. However, with the price of rare earth magnets continuously increasing, ferrite magnets are used to replace rare earth magnets to reduce the cost. Surface mounted magnet motors with ferrite magnets, which have lower magnetic strength than rare earth magnets, cannot meet the requirements for some applications that need high energy density.
To meet the energy density improvement goals, internal permanent magnet (IPM) motors with high power density have been developed. In the IPM motor, the permanent magnets are usually radially embedded in the rotor core.
An objective of the present invention is to provide a new IPM rotor with high power density.